auth-utils: Fixing memory leak (release transaction mutex after references are 0)

[purpshell]

Context: #2151 sparked an internal discussion within myself regarding the memory leak we are facing.

Problem: We are facing a memory leak after the first few release candidates.

Motivation: #2151 seemed like it was headed in the right direction, but as soon as I saw that it was actually producing race conditions, I knew the fix to the confirmed leak wasn't there. I also realized that the make-mutex file hasn't been edited for years and likely not the reason why Baileys is leaking.

Rushing to try and think where this leak could be, I remembered my experimental addTransactionCapability rewrite (this system fucking sucks and will be removed from Baileys entirely).

And there it was, confirmation: The addTransactionCapability function was never clearing any of the mutexes with 0 references to them.

It remains to be seen if this patch is correct - I whipped it up directly. It also remains to be seen if #2151 is going to get merged with this PR or not, as that function needs complete removal or modernization.

Please test this out on your sessions, it will likely have 0 stability impact due to us just running a clearing function on empty mutexes. This is still an experimental change, and please run some sort of perf monitoring tool for hours.

PS: Please support my work on GitHub Sponsors, as it takes a lot of prioritization to drop my exams and focus on this for 2 hours in a row. https://purpshell.dev/sponsor

[whiskeysockets-bot]

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📦 To test this PR locally:

# NPM
npm install @whiskeysockets/baileys@WhiskeySockets/Baileys#fix/mem-leak

# Yarn (v2+)
yarn add @whiskeysockets/baileys@WhiskeySockets/Baileys#fix/mem-leak

# PNPM
pnpm add @whiskeysockets/baileys@WhiskeySockets/Baileys#fix/mem-leak

If you encounter any issues or have feedback, feel free to comment as well.

[YonkoSam]

you should use the same map for both the mutex and refCount its 100% safe against race conditions

[renatoiub]

One place where I see a serious memory leak is in the event buffer; each upsert keeps accumulating until it consumes a huge amount of memory. I think the problem is there.

[purpshell]

One place where I see a serious memory leak is in the event buffer; each upsert keeps accumulating until it consumes a huge amount of memory. I think the problem is there.

I saw a new PR lately that fixes this, I think I approved it
EDIT: #2160

[Salientekill]

One place where I see a serious memory leak is in the event buffer; each upsert keeps accumulating until it consumes a huge amount of memory. I think the problem is there.

I saw a new PR lately that fixes this, I think I approved it EDIT: #2160

Not yet approved 🫡